Analysis Of Wire Antennas Research Articles

Method of Moment Analysis of Wire Antennas Based on Different Basis Function

For the study of highly precise simulation algorithm for the analysis of antenna, the basic thought of method of moment analysis of wire antennas is introduced. The mathematical model is established and the formula derivation is presented in this paper. The method of moment equation is solved through utilizing three different basis functions and weight functions. Two examples are given, and the computing results are contrasted with the simulation results of FEKO. The comparison result shows that method of moment is quite accurate when it is used to analyze wire antennas, and the computed results acquired by applying Galerkin matching method are the most accurate of all. In the end, an accurate and effective electromagnetic simulation method is presented.

Solution of an integral important in the analysis of wire antennas above ground

Analytical solution of an integral important in the analysis of wire antennas above ground is presented in detail. The integral plays an important role in numerical analysis of wire antennas, because for small source-to-field distances it is quasi-singular and thus very demanding for numerical integration. Therefore, its exact analytical solution is preferred.

A General Method for the Analysis of Curved Wire Antennas

A general method for the analysis of curved wire antennas, based on Method of Moments (MoM) with curved segments is presented. The method applies to wires that can be represented as a function of an arbitrary parameter. Computational procedures for the analysis of wire antennas and the results for cylindrical, conical, and hemispherical helical antennas are presented. Advantages and disadvantages of the method are discussed.

On the Use of Spatio-Temporal Wavelet Expansions for Transient Analysis of Wire Antennas and Scatterers

To analyze a wire antenna excited by a time varying voltage source or a wire scatterer excitated by transient electromagnetic incident wave, the problem is formulated in terms of a time-domain integral equation for the induced current. To solve the integral equation, we reduce it to matrix equation via the method of moments using the known-to-be-stable implicit scheme. However, rather than directly constructing and solving the relatively large matrix equation, we propose an iterative procedure which allows us to gradually obtain a solution of refined accuracy both everywhere and simultaneously at any time instance. To render this procedure rapidly converging, we use a basis of spatio-temporal wavelet functions. This basis facilitates a good approximation of the induced current using far less basis functions than would be needed if other expansions, such as standard-pulse or Fourier basis functions were chosen. The use of this basis further enables the iterative procedure to increase the temporal and spatial resolutions where required without unnecessarily affecting their levels elsewhere.

Efficient analysis of wire antennas and scatterers with arbitrary shape

The efficient analysis of wire antennas of arbitrary shape is presented. The exact kernel representations of Green's function are given in place of the thin-wire approximation kernel for the moment method solution of arbitrary wire antennas and scatterers with moderately large radius. The kernel expressions are exactly expanded on the basis of series summations so that the elements of the impedance matrix can be evaluated accurately and quickly. Some numerical examples are performed for validation of the efficiency and accuracy of the proposed method.

Modeling of a cylindrical wire antenna with flat end caps using a rigorous moment method technique

With recent capabilities for accurately and efficiently modeling electrically thicker wire antennas, questions concerning the necessity of including end caps in the model have resurfaced. The finite charge on the ends, which can significantly affect the current distribution, as well as improve convergence and stability of the solution, has been characterized in the past by several approximate models. However, a more in‐depth analysis of a wire antenna with end caps is necessary for completely characterizing the end charge density and understanding its effects on the near‐field behavior and the current distribution of the wire. Such a treatment is especially important for moderately thick wires or resonant structures. A rigorous method of moments formulation is developed in this paper for the analysis of cylindrical wire antennas with flat end caps. Circumferentially invariant axially directed trigonometric current basis functions are assumed on the cylindrical surface, and pulse charge density basis functions are assumed on the end caps. In addition, the formulation introduces a ring charge at the outer boundary of the top and bottom end caps to account for the edge discontinuity. Exact analysis techniques are employed to obtain the solution to the electric field integral equation.

Numerical integration method in analysis of wire antennas

The numerical evaluation of an integral is a frequently encountered problem in antenna analysis. A special Gauss-Christoffel quadrature formula for nonclassical weight function is constructed for solving the pseudo-singular integration problem arising from the analysis of thin-wire antennas. High integration accuracy is obtained at comparable low computation cost by the quadrature formula constructed. This integration method can be also used in other electromagnetic integral equation problems.

A basic theorem that simplifies the analysis of wire antennas

The basic concept of the differential current element is extended to obtain an equally basic but more easily applied concept with which to characterize antenna behavior. The extension is accomplished by applying mathematical induction, using only algebra and a few well-known trigonometric identities.

General entire-domain Galerkin method for analysis of wire antennas in the presence of dielectric bodies

A novel, entire-domain moment-method is proposed for the analysis of wire antennas and scatterers in the presence of lossy inhomogeneous dielectric bodies of finite extent. The wire part of the structure is approximated by arbitrarily positioned and interconnected straight-wire segments of lengths which can exceed one wavelength. The dielectric bodies are approximated by a system of trilinear hexahedrons, which can be electrically large (can also exceed one wavelength inside the dielectric, in any direction). The current along wires and inside dielectric bodies is approximated by one- and three-dimensional polynomials, respectively. The unknown current-distribution coefficients are obtained by a Galerkin-type solution of the system of coupled two-potential integral equations. The method is accurate, efficient and reliable. Its fundamental advantage over the (only existing) subdomain methods for the analysis of the same type of structures is a significantly reduced number of unknowns and, consequently, greatly reduced computing time. The proposed method enables rapid analysis of wire/dielectric structures exceeding moderate electrical size with even standard personal computers.

Considerations on feed expressions for the numerical analysis of antennas

AbstractAntennas having highly complicated configuration can be analyzed numerically by the recently proposed moment method and/or remarkably improved computer system, and many analyzed results have also been reported. However, on the other hand, some problems, such as convergence in the moment method, numerical solution of a current distribution feed point, and nonphysical oscillations at an edge, have been pointed out. Although in the analysis of wire antennas, assumptions of slice generator, finite gap generator, or annular ring of magnetic current are used adequately as a feed, it is necessary to know how different is the numerical calculation between them. This paper considers an integral equation obtained with a boundary condition at antenna surface and axis, and an integral equation obtained using an axis current approximation. These integral equations were calculated numerically for a linear dipole antenna applying the moment method. As a result, the difference of numerical solution by a difference of feed formula was clarified.

Simple method for analysis of dielectric-coated wire antennas

A simple method is presented for analysis of wire antennas assembled from arbitrarily interconnected straight-wire segments, which are completely or partially covered with a dielectric coating. The thickness of the coating is assumed to be not larger than about the radius of the wire, and its relative permittivity not larger than 10. The method is based on the so-called two-potential integro-differential equation combined with polynomial approximation of current. Numerical results are found to be in very good agreement with experiments.

Correction to WIRES program

The WIRES computer program as reported in [2] has seen wide use in the analysis of wire antennas. However, errors exist in the program's treatment of a wire (or wires) incorporating radius changes. Simple corrections are presented to eliminate these errors.

Analysis of Wire Antennas in the Presence of a Conducting Half-Space. Part II. The Horizontal Antenna in Free Space

An integral equation approach for the analysis of a horizontal wire antenna(s) located in free space near a lossy half-space is described. Two methods, a rigorous one based upon the Sommerfeld formulation and an approximation technique involving the Fresnel plane-wave reflection coefficients, are used to account for the influence of the interface-reflected field upon the antenna current distribution. A moment method (subsectional collocation) solution procedure is used to obtain numerical results for antenna impedance and radiation patterns. The reflection coefficient approach is found to agree well (generally within 10%) with those due to the rigorous method at a fraction (approximately 1%) of the computer cost.

Analysis of Wire Antennas in the Presence of a Conducting Half-Space. Part I. The Vertical Antenna in Free Space

An integral equation method (based upon the electric field) for the analysis of a vertical antenna located in free space near the interface with a lossy half-space is presented. Two methods are considered to account for the influence of the interface-reflected fields upon the antenna current distribution: (1) the rigorous Sommerfeld integral approach and (2) a plane-wave reflection coefficient approximation. Numerical results for antenna impedance from the two methods are compared. It is found that for the parameter variations studied, the reflection coefficient approximation provides results within 10% of those obtained from the rigorous approach at approximately 1% of the computer time. The reflection coefficient technique has the further advantage of being readily extended to arbitrary antenna geometries and orientations.